Assess your learning. Start with the "Important Terms and Concepts" to ensure you know the terminology related to the topic of the chapter and concepts discussed. Move on to the "Review Questions" to answer critical thinking questions about concepts and processes discussed in the chapter. Finally, test your overall understanding by taking the "Self-assessment quiz".
- the outer most sphere where gases are distributed in distinct layers by gravity according to their atomic weight
- lies between the Earth's surface and the heterosphere. Gases are nearly uniformly mixed through this layer even though density decreases with height above the surface
- Constant Gases
- Nitrogen, oxygen and argon are called the "constant gases" because their concentration has remained virtually the same for much of recent earth history
- Variable Gases
- those present in small and variable amounts. These include carbon dioxide, methane, ozone, water vapor, and particulates among others.
- O3 is both beneficial and harmful to life on Earth
- Carbon dioxide
- (CO2) makes up only .036% of the atmosphere by volume. Carbon dioxide is essential to photosynthetic processes of plants.
- (CH4) is a greenhouse gas contributing to about 18% of global warming and has been on the rise over the last several decades. Methane is a product of the decomposition of organic matter, with major natural sources being that which occurs from wetlands, termites, the oceans, and hydrates.
- Particulates (and aerosols)
- very small particles of solid or liquid suspended in the air
- Water Vapor
- an extremely important gas found in the atmosphere.
- Environmental lapse rate (ELR)
- The rate of change in temperature with altitude
- Normal lapse rate of temperature
- the average value of the ELR, .65o C /100 meters
- Inverted lapse rate of temperature (inversion)
- when the air temperature actually increase with an increase in altitude above the Earth
- the layer closest to the Earth's surface
- lies above the troposphere. Here the temperature tends to stay the same with increasing height.
- Above the tropopause lies the stratosphere. Through most of the stratosphere the air temperature increases with an increase in elevation creating a temperature inversion
- air temperatures begin to decrease with increasing altitude
- above the mesosphere. air temperature increasing with increasing altitude
- not really a layer of the atmosphere, but an electrified field of ions and free electrons
- also called the "ozone layer", is the concentrated layer of ozone found in the stratosphere
- Greenhouse effect
- longwave radiation emitted from the Earth's surface and directed toward the sky is readily absorbed by greenhouse gases. When absorbed, the temperature of the atmosphere increases. Some of this absorbed energy is emitted to space while some is emitted back towards the Earth.
Explain how the greenhouse effect works.
Shortwave radiation penetrates through the atmosphere and is absorbed by the surface. The surface radiates longwave radiation toward the atmosphere. The atmosphere absorbs this energy and radiates it back down toward the surface. Increasing "greenhouse gasses" though human activities traps more radiation causing an increase in near-surface temperatures.
Briefly describe how temperature changes from the surface up to the mesosphere.
Troposphere: temperature decreases with an increase in elevation. Tropopause: no change in temperature with an increase in elevation. Stratosphere: temperature increases with an increase in elevation. Stratopause: no change in temperature with an increase in elevation.
What impact do particulates have on the atmosphere?
Particulates can reflect incoming shortwave and cause atmospheric cooling. They are also good absorbers of terrestrial earth radiation which would cause atmospheric warming. Particulates serve as condensation nuclei.
What is an inversion?
An inversion occurs when air temperatures increase with an increase in elevation. Inversions can occur under the right conditions in the troposphere. The stratosphere is noted for its inversion.
What is the environmental lapse rate of temperature?
The environmental lapse rate of temperature is the decrease in temperature with an increase in elevation through the troposphere. The temperature decreases with elevation because the earth is the immediate source of energy to heat the air.
How do humans contribute to global warming?
Fossil fuel burning (e.g., emissions from transportation and energy generation), deforestation, cattle farming and rice production to name a few.
What impact does ozone at the surface have on humans?
Ozone is an eye irritant and causes shortness of breath due to constricting air ways in the throat and lungs.
Explain why temperatures increase with height through the stratosphere.
Because ozone absorbs incoming solar radiation. The top of the stratosphere is hotter because its closer to the source of shortwave radiation. An ever diminishing amount of shortwave radiation as it passes through the stratosphere causes the temperature to decrease toward the bottom.
Describe how clouds impact climate.
Clouds can reflect solar radiation off the top of the cloud causing atmospheric cooling. They are good absorbers of terrestrial earth radiation which would cause atmospheric warming. The role of clouds in climate change is one of the most vexing problems to climate scientists.
Where does methane came from and what role does it play in the atmosphere?
Methane is a product of the decomposition of organic matter, with major natural sources being that which occurs in wetlands, melting permafrost and as a by-product termite actvities. Methane is a greenhouse gas.
- Free ____ is a product of plant photosynthesis.
- carbon dioxide
- The concentration of carbon dioxide in the atmosphere
- is generally higher during the winter.
- has increased in the last 100 years
- is a greenhouse gas
- all the above
- Greenhouse gases
- are good absorbers of solar (shortwave) radiation.
- are good absorbers of longwave radiation emitted by the Earth.
- absorb shortwave and longwave radiation equally well.
- absorb neither shortwave or longwave radiation.
- Temperatures tend to ______ through much of the stratosphere.
- increase with an increase in elevation
- decrease with and increase in elevation
- stay the same with an increase in elevation
- None of the above
- Clouds are good absorbers of
- longwave radiation emitted by the earth
- UV light
- none of the above
- Termites are thought to be a source of
- carbon dioxide.
- none of the above.
- Which of the following is considered a "permanent gas"?
- Carbon dioxide
- None of the above
- serve as condensation nuclei.
- can cause atmospheric cooling.
- can cause atmospheric warming
- can do all the above.
- Most of the ozone found in the atmosphere is found in the
- An inversion
- is where temperatures increase with increasing altitude.
- is where temperatures decrease with increasing altitude.
- is where temperatures stay the same with increasing altitude.
- is where temperatures increase with decreasing altitude.
Use these resources to further explore the world of geography
- Focus on The Physical Environment: "The Carbon Cycle. NASA Earth Observatory" Elizabeth Kolbert, staff writer, The New Yorker WGBH Forum
- Physical Geography Today: AIRNow - real time air quality data (US EPA)
- World of Change: Antarctic Ozone Hole
"The Precious Envelope" (Annenberg/CPB) The World of Chemistry video series "The Earth's atmosphere is examined through theories of chemical evolution; ozone depletion and the greenhouse effect are explained. (Material is somewhat dated but still useful.)
Go to the The World of Chemistry site and scroll to "The Precious Envelope". One-time free registration may be required.
The Ozone Layer: Closing the Gap (NASA, 2019) "In the 1980s, scientists began to realize that ozone-depleting chemicals, such as chlorofluorocarbon (CFCs), were creating a thin spot—a hole—in the ozone layer over Antarctica. Through an international effort to decrease the use of CFCs, the ozone layer is starting to mend, and scientists believe it should mostly recover by the middle of the 21st century. This series of satellite images shows the ozone hole on the day of its maximum depth from 1979 through 2018."